Thermostatic element



Oct. '30, 1928.

Temperature Goeffi'pien? of Expa 'P. H. BRACE THERMOSTATIC ELEMENT Filed March 12. 1926 WITNESSE S:

' I l l I00 200 '300 400 Cemfymde.

HNVENTOR Par zer' H Brace.

TORNEY 40 perature and 300 C.-1s.a proximately equal p ordinary temperatures below 100 C. is very Patented Oct. 30,

4 1,689,814. I UNITED "STATES PATENT OFFICE.

ron'rnan. names, or wnlmsnnm, IEN'NBYlSVANIA, xssre'non 'ro wnsirmenousn ntncraro a MANUFACTURING-COMPANY, a conronarron or rmmsnvanm 'rnnmlos'm'rrc ELEMENT.

"Application filed Iareh 12, 1826. Serial Io. 84,198.

rature-re- My invention relates to tem to alloys sponsive devices, and particular y for bimetallic members therefor.

' An object of my invention is to provide an 5 alloy --for bimetallic devices that is characterized by a low temperature coefliclent of expansion over a wide range of temperature.

In practicing my invention, I provide an alloy fora bimetallic member the prmclpal components of which-are iron, nickel cobalt and a minor portion of manganese. The temperature coefiicient of expansion of the alloy comprising the above named elements is substantially constant between room temperatures and 300 C. The value of the temperature coeflicient of expansion over the ran e between 0 C. and. 300 C. is substantm y equal to that of invar at ordinary tempera- "tures.

1 Between 0 C. and 100 C. the temperature coeflicient of expansion of invar is approxlmately 1 to2 m1llionths of its length per degree centigrade.

of expanslon will reach approximately 5 w millionths of its len h per degree centigrade, and at 300 C., it w' 1 increase to substantially 12 liillionths of its length per degree cent1- gra e. p

, I have found thatthe addition of cobalt to the nickelsteels profoundly alters the expansivity or the tem rature coeflicient of expansionand that, if alloys are prepared havin iron, nickel and manganese ratios containe in invar and a substantial proportion of cobalt, it is possible to secure alloys having practically uniform temperature coefiicients of expanslon between room tem 'rature and 300 C. The value of the coe cient ofexbetween room tem- .pansion over the ran tothat of invar at ordinary temperatures.-

' I provide also as a cooperating element for my new alloy, a metal which has a rapidly increasing temperature coeflicient of expansion from room temperature to substantially 375 C. Other alloys which may! be used with the above iron, nickel, cobalt and mannese alloy are Monel metal,stainless iron,

I which is a low carbon-iron-chromium alloyso containing from 14% to 20% chromium and cobalt, and the-cobalt, chromium or tungsten alloys commonly known as stellite.

v In the accompanying drawing which re resentst e ature cient of expansion to'the'tempera- 11 is a curve At 200 0., the coeflicient v and 375- relation of the temperture to which the alloy of my invention is subjected." For my improved alloy, the temperature c'oeflicient of expansionis substantially 'constant from 0 C. to 300 C. and from 300 C. to substantially 500 C. the temperature coeflicient of expansion increases very rapidly and is proportional to the temperature.

A-specific form of the alloy represented by the curve 11 contains a proximately 58% non, 32.6% nickel, 9% co alt and 4%. man- I ganese.

By decreasing the nickel content and increasing the iron and cobalt content of the. alloy represented by the curve 11, it is possible to shift the horizontal portion 12 ofthe curve 11 so that it extends from minus 100. C.

to plus 200 C. Fortemperatures exceeding 200 'C., the rtion 14 of the curve is sub stantially of t e same shape as the portion 13 of the curve 11.

' In order to obtain the characteristics set forth above, the iron and nickel elements of the alloy may be varied from and between the to 1 part of nickel ratios of 3 parts of iron and 1 part of iron to 1 part of nickel; the

'cobalt content may bevaried from 1% to 20%,and the manganese may be varied from A curve 15 re resents the relation of the temperature coe cient of expansion to temperature for metal such as invar, and a curve 16 represents the relation of the temperature coeflicient of expansion to temperature for a metal alloy such as Monel.

In providing a thermostatic material in bimetallic form which comprises invar steel and my improved alloy represented by 'the curve 11, I have found that the difl'erence between the temperature coeflicients of said alloys at small, but between 100 C. and 400 C. there is a marked increase in the diflerence between the temperature coefiicients thereof. It is readily seen from-the drawings that the difference in temperature coeflicients of expansion is substantially pro ortional to the temperature between .and 375 C. A bimetallic material composed of these two metals is suitable to operate as a thermostat.

over a tem rature range between 100 (1.,

because the lar change'between the temperature ooefliclents of expansion takes place between those two temperature limits. At temperatures below 100 0.,

limited to the use of invar or Monel metals therewith. Some of the metals, other than those hereinbefore mentioned, that may be used in cooperation with the metal represented by the curve 11 are pure nickel, nickel-steel or brass.

My present application is closely related, to my copending application Serial No. 192,559, filed May 19, 1927, in which the particular alloy represented herein by the temperature ex ansivity curve 11 is described and claimed.

arious modifications may be madein m invention without departing from the spirit and scope thereof. I desire, therefore, that such limitations shall be placed thereon as are imposed by the prior art and the'appended claims. 4

I claim as my invention:

1. A temperature-responsive device com prising metallic elements, one of said elements ingan alloy of nickel having relatively igh temperature coeflicient of expansion, and the other of said elements being an alloy which contains iron and nickel inv the ratios of from 3 parts of iron to 1 part of nickel and cobalt in amounts varying from 1% to 20% of the alloy content.

2. A temperature-responsive device comprisin metallic elements, one of said elements ing an alloy of nickel havin a relatively high tem erature coefficient 0 expansion, and the ot er of said elements being an alloy which contains iron and nickel in the ratios of from 1 part of iron to 1 part of nickel and-cobalt in amounts between 8% to 12% of the alloy content.

3. A temperature-responsive device comprisin metallic elements, one of said elements ing an alloy of nickel having a relatively high temperature coeflicient of expansion, and the other of said elements being an alloy which contains iron and nickel between the ratios of 3 parts of iron to 1 part of nickel to 1 part of iron to 1 part of nickel, and cobalt in amounts between 1% to 20% of the alloy content.

4:. A temperatureresponsive device comprising metallic elements, one of which is a nickel steel and the other of which is an alloy containing substantially 58% of iron, 32.6% of nickel, 9% of cobalt and 0.4% of manganese.

5. A temperature-responsive device comprising a pair of cooperating elements, one of said elements being an alloy of iron, nickel,

cobalt and one or more metals of the vanadium group, said iron and nickel being present in the ratio of 3 parts of iron to 1 part of nickel, said cobalt being present in amounts from 1% to 20% of said aggregate alloy, and said metal or metals of the vanadium group being present in amounts from 0.1% to 0.8% of said alloy content, andthe other of said elements being a nickel steel alloy.

6. A temperature-responsive device comto 20% of said aggregate alloy, and said metal or metals of the chromium'group being present in amounts from 0.1% to 0.8% of said alloy content,'and the other of said elements I being a nickel steel allofy.

In testimony whereo I have hereunto subscribed my name this 4th day of March, 1926.

PORTER H. BRAOE. 

